Diamantane derivatives have found various useful applications. For example, in the field of electronic materials, with the progress of high integration, multifunction and high performance, circuit resistance and condenser capacity between wirings have been increased thus causing increase of electric power consumption and delay time. Reduction of parasitic resistance and parasitic capacity are in demand for the purpose of attaining acceleration of devices by reducing this delay time. As one of the concrete measures for reducing this parasitic capacity, an attempt has been made to cover periphery of wiring with a low dielectric interlayer insulating film. Also, the interlayer insulating film is required to have superior heat resistance which is enough to withstand the thin film formation step at the time of producing mounting substrates. Since diamantane has a small electronic polarization and has a rigid, diamond-like saturated hydrocarbon structure, it is known to be useful as a constituent of an interlayer insulating film having low dielectric constant and high heat resistance. As one example thereof, reference may be made to US Patent Application Publication No. 2005/276964.
In synthesizing useful diamantane derivatives having various functional groups, brominated diamantanes play an important role as intermediates for synthesis of the derivatives. That is, a bromine atom on diamantane can be converted to a OH group, an amino group, a SH group, a carboxyl group, a formyl group, an acyl group, an amido group, an ethynyl group, an alkyl group, an aryl group or the like.
Regarding processes for synthesizing bromine-substituted diamantanes, there have been made several reports. For example, as is described in Journal of Organic Chemistry, 39, 2987-3003 (1974), a process of synthesizing a mono-bromodiamantane, a dibromodiamantane, a tribromodiamantane and a tetrabromodiamantane by acting bromine in the presence of a catalytic amount of aluminum bromide has been disclosed. Of these, the dibromodiamantane is known to include three isomers of 1,4-dibromodiamantane, 4,9-dibromodiamantane and 1,6-dibromodiamantane. It has been difficult to selectively synthesize 4,9-dibromodiamantane alone in high yield among them, and no effective processes have been known. An attempt to synthesize 4,9-dibromodiamantane under conventionally known conditions results in simultaneous production of other dibromodiamantane isomers and monobromodiamantanes and tribromodiamantanes as well as 4,9-dibromodiamantane. Purification of such product by repeating recrystallization or column chromatography results in a serious reduction of yield, and the purified product has only insufficient purity. Also, in the above-described process, generation of heat in the bromination reaction is so large that it is difficult to control the inside temperature, thus scale-up of the reaction being difficult. In addition, bumping of bromine might threaten safety of workers. Thus, in view of these points and industrial productivity, it has been demanded to largely improve the process.